a. The Field of the Invention
This invention relates to the art of marking surfaces which are exposed to mark-obliterating traffic, and more particularly to the provision of traffic lines and other directional data upon the road surface of streets and highways, by applying and securing road marking material on said road surface, whereby a marked road is provided.
B. The Prior Art
This art is well worked and widely known. The marks, most commonly traffic lines, can be painted on the road surface, formed thereon by applying molten material thereto, or provided thereon by applying and adhesively securing preliminarily manufactured tape material thereto. The thus formed or applied traffic line or other mark will therefore form of itself a part of the road surface and will be correspondingly subjected to the wear and progressively destructive action of traffic, particularly where such traffic includes the passage of fast and/or heavy vehicles.
The problems involved in providing a roadway surface marking material having both high visibility and non-skid properties have been extensively discussed and analyzed in the instant Applicant's prior British Pat. Specification No. 1,032,813, Canadian Pat. No. 754,343 and in the U.S. Pat. No. 3,399,607 of the United States of America. In these prior Patents it is proposed to provide a compound marking material, the upper or exposed surface of which includes different parts arranged thereon, some of these parts being substantially smooth and suitably pigmented to provide high light reflectivity and, thus, visibility, but having poor non-skid properties, while the remaining parts are formed of a compound having a high content of substantially hard and granulated components, such as sand and quartz, to provide fairly good non-skid properties, such latter parts however providing poor visibility and being undesirably receptive to dirt, rubber particles from vehicle tires and so on.
The Applicant has more recently proposed an improved structure of the above road marking materials, such as described and open to public inspection in the French Pat. No. 2,097,941, Belgian Pat. No. 768,577 and in the published German Patent Application No. P 21 30 529.3. According to this more advanced technology, there has been provided a road marking material comprising a base compound of essentially elastomeric nature, including a first binder and having a smooth, substantially planar and highly light-reflective surface adapted to face away from the road surface, a plurality of particles having a hardness substantially higher than 7 on the Mohs' Hardness Scale and each including a lower portion embedded in and securely bonded to said base compound and an upper portion extending outwardly from said surface and comprising a pointed end portion, said pointed end portions being spaced from one another by a substantial distance and imparting good anti-skid properties to said surface, the bond of said particles to said base compound and first binder being ensured by a second binder wetting said particles when contacted therewith and being compatible with said first binder. These prior patent publications describe also that said base compound is in the form of a tape, the second binder entirely coats the particles and the thus coated particles are dispersed within said base tape. There has been described also that such particles preferably consist of beryllium or corundum crystals and have a particle size from one tenth to one millimeter. There has been further described that the second binder comprises epoxy resins, polyester resins, acrylic resins, methacrylic resins, polyvinyl butyral and inorganic binders added to chlorinated rubber.
It is therefore an object of this invention to provide a further improved prefabricated road marking material, having an upper surface and a plurality of upwardly turned pointed hard particles partially extending outwardly from said surface, the new material providing unexpected sharp improvements in anti-skid, wear resistance and high visibility properties.